The present invention concerns machinery for discontinuously forwarding material or work past or through discontinuously operating tools, presses for example. Two separated workholder bars parallel the forwarding stream. The bars move upstream and downstream together subject to a cam. The cam rotates around an axis paralleling the stream. The motion of the cam is transmitted to the bars by a follower and by a transmission that engages guides that guide the bars. The bars are accordingly discontinuously shifted in at least one direction essentially cross-stream.
Machinery of this type and for this purpose is known from German OS 2 206 407. The work-holder bars move upstream and downstream together and toward and away from each other cross-stream. Each motion is generated by a different cam. The cams are mounted tight on the same shaft, which extends parallel with and below the work-holder bars.
The upstream and downstream motions of the work-holder bars in this machinery are derived from an axial cam and transmitted to cross-stream work holder-bar guides by way of a thruster. The thruster and guides move stream-parallel. The cam generating the toward-and-away motion that opens and closes the work holder on the other hand is a radial cam. The transmission for the cross-stream drive mechanism comprises two cogwheels positioned immediately above the cam. Each cogwheel meshes with the other and with a rack that extends across the gripper bars. A follower that operates in conjunction with the cam rests against the circumference of the engaging cogwheels.
This known forwarding machinery is simple and reliable and has been well proven. It does have drawbacks, however. It is noisy, and the cogs wear out after a while, which leads to even more noise along with imprecision in the motions of the work-holder bars.